1. Field of the Invention
The present invention relates to an organic light emitting display and a fabrication method thereof and, more particularly, the present invention relates to a thin organic light emitting display having a reduced fabricating process time and can prevent a substrate from being bent and damaged during the fabricating process.
2. Description of the Related Art
Generally, an organic light emitting display self-emits light by causing an electric current to flow through a fluorescent or phosphorescent organic compound and allowing an electron and a hole to be coupled to each other. Moreover, an organic light emitting display can display an image by driving organic light emitting diodes, for example, n by m organic light emitting diodes, by a voltage or a current.
As illustrated in FIG. 1, organic light emitting diodes have a basic structure including an anode (ITO), an organic thin layer and a cathode electrode (metal). The organic thin layer is composed of an EMitting Layer (EML) which emits light when the electrons and the holes meet and thereby form an exciton, an Electron Transport Layer (ETL) for controlling the moving speed of the electrons, and a Hole Transport Layer (HTL) for controlling the moving speed of the holes. An Electron Injecting Layer (EIL) is further formed in the ETL for improving the effectiveness of the injection of electrons, and, a Hole Injecting Layer (HIL) is further formed in the Hole Transport Layer for improving the effectiveness of the injection of holes.
The organic light emitting display is by no means inferior to other devices because of a wide range of vision, a super high-speed response, and spontaneous light emitting, and it is possible to fabricate a thin light-weight device since the power consumption is low and a backlight is not required. Since it is fabricated at a low temperature and the fabricating processes are simple, the device is fabricated at a low cost. As an organic thin layer material technology and the process technology are being developed rapidly, they are considered to be the technology which can replace the conventional flat display device.
Meanwhile, since electronic devices, such as cellular telephones, Personal Digital Assistants (PDAs), notebook computers, computer monitors, televisions and so forth, have becomes slimmer, it is necessary for the organic light emitting display to have a thickness below about 1 mm. However, in the present organic light emitting displays, since a protective layer technology that can substitute for an encapsulation technology has not been sufficiently developed, it is difficult to fabricate an organic light emitting display having a thickness below 1 mm.
In order to fabricate the organic light emitting display having a thickness below 1 mm, Japanese Laid-Open Patent Publications Nos. 2005-340182, 2005-222930 and 2005-222789 relate to a method of fabricating a thin organic light emitting display in which element layers (a semiconductor layer and an organic light emitting diode, etc.) are respectively formed on two glass substrates, and the glass substrates are then bonded to each other so that the respective element layers face each other and then the surfaces on which the element layers are not formed are removed by an etching or grinding process.
However, the above-noted fabricating method has a problem in that the fabricating process time greatly increases because after the semiconductor layer or the organic light emitting diode is formed on the respective glass substrates, the glass substrates are bonded to each other and are etched or ground. Moreover, such a conventional fabricating method has a problem in that the yield of production is low and the fabricating cost is expensive because the partly finished glass substrates are bonded to each other and the glass substrate, the semiconductor layer and the organic light emitting diode is damaged during bonding process.
A fabricating method is conceivable in which after providing a glass substrate having a thickness below 1 mm, an element layer is formed on the surface of the glass substrate. However, such a fabricating method has a problem in that the glass substrate bends or contacts a moving device and is damaged during the moving process because the glass substrate is very thin.